Abstract

AIM: To validate a combined disc method along with resazurin chromogenic agar for early screening and differentiation of Klebsiella pneumoniae carbapenemase, metallo-β-lactamase and OXA-48 carbapenemase-producing Enterobacteriaceae. METHODS AND RESULTS: The combined disc test comprising of meropenem alone and with EDTA, phenylboronic acid, or both EDTA and phenylboronic acid, and temocillin alone were evaluated with the resazurin chromogenic agar plate assay against a total of 86 molecularly-confirmed Enterobacteriaceae clinical isolates (11 metallo-β-lactamases, 8 Klebsiella pneumoniae carbapenemases, 11 OXA-48, 32 AmpC and 15 extended-spectrum-β-lactamase producers and 9 co-producers of extended-spectrum-β-lactamase and AmpC). The inhibition zone diameters were measured and interpreted at seven hours for the presence of carbapenemase. All carbapenemase producers were phenotypically distinguished by this assay with 100% sensitivity and specificity. CONCLUSIONS: This early phenotypic method is very simple, inexpensive, and reliable in the detection and differentiation of carbapenemase-producing Enterobacteriaceae. It could be exploited in any microbiological laboratory for diagnosis of these recalcitrant bacteria. SIGNIFICANCE AND IMPACT OF STUDY: This assay poses excellent performance in discrimination of Klebsiella pneumoniae carbapenemase, metallo-β-lactamase and OXA-48 carbapenemases within seven hours, which is much faster than conventional disc diffusion methods. The rapid detection could help clinicians screen patients, control infection, and provide epidemiological surveillance. This article is protected by copyright. All rights reserved.

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Additional Information:

This is the accepted version of the following article: Teethaisong, Y., Eumkeb, G., Nakouti, I., Evans, K. and Hobbs, G. (2016), A combined disc method with resazurin agar plate assay for early phenotypic screening of KPC, MBL and OXA-48 carbapenemases among Enterobacteriaceae. J Appl Microbiol. Accepted Author Manuscript. doi:10.1111/jam.13196, which has been published in final form at http://dx.doi.org/10.1111/jam.13196